1. A working machine comprising:
a base machine, which is formed in such a manner that an upper rotating body is rotatably mounted on a crawler type lower traveling body around a vertical shaft, the base machine including a working attachment comprising a boom, an arm, a bucket, and driving motors for the boom, arm and bucket, said upper rotating body having an operator’s cab on an upper portion of said upper rotating body, said upper rotating body having functional apparatus which requires maintenance comprising an openable guard cover, which covers the apparatus, attached to an outer peripheral portion of the upper rotating body of said working machine;
a window provided in said guard cover for maintenance of said apparatus;
a window cover provided with said guard cover, said window cover being provided to open or close said window independently of opening or closing of said guard cover; and
a guard cover locking mechanism, provided within said guard cover, which locks said guard cover in a closed mode, said guard cover locking mechanism being located within said guard cover to allow a locking and an unlocking operation from the outside of said guard cover only through said window.
2. The working machine according to claim 1, wherein a window cover locking mechanism is provided, which locks said window cover in a locked mode and unlocks said window cover in an unlocked mode by a key operation from the outside of said guard cover.
3. The working machine according to claim 1, wherein said guard cover locking mechanism is provided in an inner side edge of said window in such a manner that the mechanism is located within a visible scope through said window in an open mode.
4. The working machine according to claim 1, wherein the apparatus covered with said guard cover are separated into high frequency maintenance apparatus and low frequency maintenance apparatus on the basis of frequency of maintenance as a standard, and said high frequency maintenance apparatus are disposed in such a manner that a maintenance work can be done through said window.
5. The working machine according to claim 4, wherein said high frequency maintenance apparatus include one of a selector valve which changes a direction of oil flow in accordance with an working attachment attached to said body, a multi control valve which changes an operating pattern of an actuator for said working attachment, and a level gauge for a working oil tank.
6. The working machine according to claim 4, wherein said working oil tank is disposed facing said window and said high frequency maintenance apparatus are attached to an outer wall surface of the working oil tank.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A semiconductor storage device comprising an SRAM cell having a first inverter, a second inverter with an input terminal and output terminal connected to an output terminal and input terminal of said first inverter respectively, a first pass transistor provided in a path between said output terminal of said first inverter and a first bit line, a second pass transistor provided in a path between said output terminal of said second inverter and a second bit line, and a word line connected to gates of said first and second pass transistors;
wherein said SRAM cell comprising:
a third pass transistor provided in a path between said first pass transistor and said first bit line;
a fourth pass transistor provided in a path between said second pass transistor and said second bit line; and
a voltage applying unit applying a first voltage to said word line at the time of a read operation of said SRAM cell, and applying a second voltage larger than said first voltage to said word line at the time of a write operation of said SRAM cell.
2. The semiconductor storage device according to claim 1, wherein said voltage applying unit comprises a decoder outputting said first voltage, and a step-up circuit outputting said second voltage at the time of said write operation by stepping up said first voltage outputted by said decoder.
3. The semiconductor storage device according to claim 1,
said SRAM cell further comprising:
a fifth pass transistor, of an opposite conductive type to said first pass transistor, connected in parallel with said first pass transistor; and
a sixth pass transistor, of an opposite conductive type to said second pass transistor, connected in parallel with said second pass transistor.
4. The semiconductor storage device according to claim 1, said SRAM cell further comprising:
a fifth pass transistor, of an opposite conductive type to said third pass transistor, connected in parallel with said third pass transistor; and
a sixth pass transistor, of an opposite conductive type to said fourth pass transistor, connected in parallel with said fourth pass transistor.